The output rate of the teller machine is (1 transaction/6 minutes). The input rate is (1 customer/10 minutes). This means that the machine completes a cycle faster than the customers arrive, on the average. I don't know how an average can be calculated without more information. If we assume customers arrive every 10 minutes, and no one screws up the machine, that there should be no waiting line. Is there more information about when the customers arrive? E.g., 50 arrive in the first hour the machine is open.
